Safety Information BulletinAirworthiness

ID: SW-17-29
Issue date: 2017-10-11
Source: FAA
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Sikorsky (Schweizer, Hughes) 269C, 269C-1, 269D - Landing Gear Dampers Inspection

FAA SPECIAL AIRWORTHINESS
Aviation Safety INFORMATION BULLETIN
SAIB: SW-17-29
SUBJ: Landing Gear Dampers Inspection Date: October 10, 2017
This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin alerts you, owners, operators, and certificated
repairs facilities of Sikorsky 269C and C-1, 269D and 269D Configuration “A” model rotorcraft, of
Alert Service Bulletins (ASBs) issued by Sikorsky Aircraft Corporation that recommend a one-time
Load/Stroke Test (LST) of the landing gear dampers to be performed at an overhaul or repair facility.
Improper servicing of these dampers, or their deterioration due to aging and normal wear, may lead to
severe vibration on the ground (ground resonance), and coupled with improper pilot action to
alleviate the condition, could possibly result in total loss of the rotorcraft. These LST requirements
were subsequently incorporated into the current Helicopter Basic Handbook of Maintenance
Instructions (HMI) for these rotorcraft models.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness
directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

The particular 269 models listed above incorporate landing gear dampers designed to alleviate ground
resonance. However, these dampers, if not maintained with the correct charge pressures, have been
attributed to incidents of ground resonance which resulted in major structural damage or total loss of
the rotorcraft. Therefore, Sikorsky issued the following ASBs to ensure they must pass a one-time
LST. The HMI’s were later revised to include the LST anytime the landing gear damper is serviced
or overhauled.

Alert Service Bulletin Date Model
ASB B-304 04/15/2014 S269C
ASB C1B-041 04/15/2014 S269C-1
ASB DB-056 04/15/2014 S269D and S269D Configuration “A”

Recommendations

With the above information, supported by the statistical analyses of recent accidents, we recommend
the following:

A one-time landing gear damper LST for the affected 269 models in compliance with the ASBs to
improve protection against ground resonance accidents, unless the landing gear damper has been
successfully serviced after April 15, 2014, either to the aforementioned ASB, or the updated HMI




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requirements. Furthermore, whenever a landing gear damper is removed for maintenance, a
successful LST as specified in the HMI is recommended.

- Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY
MODEL 269C per the latest Basic Handbook of Maintenance Instructions, Publication
No. CSP-C-2, Appendix C, Section 5.
- Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY
MODEL 269C-1 per the latest Basic Handbook of Maintenance Instructions, Publication
No. CSP-C1-2, Appendix C, Section 5.
- Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY
MODEL 269D per the latest Basic Handbook of Maintenance Instructions, Publication
No. CSP-D-2, Appendix C, Section 5.
- Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY
MODEL 269D Configuration “A” per the latest Basic Handbook of Maintenance Instructions,
Publication No. CSP-D-9, Appendix C, Section 5.

For Further Information Contact

Neil Doh, Aerospace Engineer, FAA, Rotorcraft Certification Service, Boston Aviation Safety
Section; 1200 District Avenue, Burlington, MA 01803; phone: (781) 238-7757; fax: (781) 238-0199;
e-mail: neil.doh@faa.gov.

For Related Service Information Contact

Sikorsky Rotorcraft Corporation; Commercial Systems and Services; Mailstop K100, 124 Quarry
Road, Trumbull, CT 06611; Attention: Product Safety Manager; fax: (817) 762-6715; email:
product_safety.gr-sik@lmco.com




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This is a partial extract of the full document - please refer to the actual report for full information.
Sources as credited.